Retired army officer Mr Bouwens,63, and his 60 year-old-wife, of Collingbourne Kingston, took on the challenge in memory of their son’s fiancée, Lucy Sands, who died in 2011.

The 28-year-old was diagnosed with malignant melanoma in 2006, and in 2010 she began to receive treatment from the Cancer Vaccine Institute and participated in a number of experimental trials of vaccines.

The couple were joined on the 5,895 metre climb to the summit by their son George, 30, daughter Lizzie, 28, and 19-year-old family friend Will Fortescue.

Mr Bouwens said: “It is difficult, if nigh-on impossible, to predict the effect of altitude on any particular individual so all that can be done is to attempt to mitigate the chance or severity of it by slowly getting one’s body used to altitude.”

They took four days to reach base camp and reached the summit at 8.20am on Monday, March 10.

He said: “Although we were all shattered and some of us were feeling the effect of altitude sickness, we were determined not to let the CVI and our donors down.”

Mrs Bouwens, a retired physiotherapist, said: “As we reached base camp, the porters came out to meet us and relieve us of our heavy rucksacks. They congratulated us and it seemed as though they were greeting us as returning heroes.”

The climbers have raised more than £10,000 and each of them funded their own part in the expedition.